Recommended
Specification for Low-Floor Buses
Introduction
- The DPTAC Recommended Specification for Buses used to operate
Local Services was first published in June 1988 and the Re-statement
of that Specification was issued in December 1993 and revised in
July 1995.
- The values and dimensions in that Specification relate to conventional
designs of bus and it was always envisaged that a separate Specification
would need to be drawn up by the Committee for wheelchair-accessible
low-floor buses. It was decided to await the initial results of the
trials in London and North Tyneside of full size low-floor buses - in
addition to the valuable experience gained on Merseyside with the first
such vehicles to be put into service in the UK. Account was also taken
of the use of some low-floor minibuses which had identified strong passenger
support.
- The Committee believes that the low-floor bus is the way forward
for urban, medium-distance inter-urban and many rural services, and
the ongoing development of improved designs will enhance the accessibility
of local public transport for all passengers. In time, satisfactory
designs with 100 % low-floors may be available and the recommendations
which follow will need to be amended to take account of such developments.
- A significant number of low-floor buses was operating in the
UK by the end of 1996. Initially, most were 11.0 to 12.0 metre long
heavyweight single deckers, but low-floor midibuses produced by all
the major manufacturers are proving very popular. Low-floor double-deckers
are likely to be available during 1997. Low-floor minibuses are also
emerging as manufacturers turn their attention to this market.
- The Committee recognises that this Specification is being published
at a time when many other developments affecting bus design and operation
are also coming forward. Accessibility Regulations under the Disability
Discrimination Act 1995, which will introduce mandatory access requirements
for new buses, will soon be circulated for consultation to the industry.
The Department of Transport's Agreed Requirements - guidance notes for
Vehicle Certifying Officers - touch on some of the same issues and the
forthcoming European Commission Directive on harmonisation of bus and
coach construction standards will also place considerable emphasis on
accessibility.
- The Committee will continue to work with the Department of
Transport to ensure that access requirements, both domestic and European,
are compatible and represent what they believe to be best practice.
In the meantime, this document will inform and guide those operators
who want to introduce wheelchair-accessible low-floor buses ahead of
legislation.
Definition of the Low-Floor Bus
- From the inception of the concept in Germany in the late 1970s
the basic feature of all low-floor buses so far produced is the step-free
layout at the entrance and exit doorways (ahead of the rear axle) and
the flat level floor between those doorway positions.
- On such buses floor heights between the two doors of about
350mm have usually been combined with entrance/exit step heights of
between 315 and 340mm reduced with kneeling suspension to between 230
and 250mm. The installation of a power-operated ramp at one door is
commonplace, to assist wheelchair-users to board and alight.
- As well as providing access for wheelchair users, the absence
of steps on low-floor buses makes them more attractive to many thousands
of passengers whose mobility is impaired. They also attract more passengers
and increase the use made of public transport - for example by parents
travelling with small children or people with heavy luggage - for whom
the low floor makes bus travel a civilised alternative to the private
car, taxi or minicab.
- At present, there exist three main approaches to low-floor
bus design. First, the use of smaller engines coupled with a low-level
drive-train to the rear axle. Second, the "hybrid" low-floor bus which
retains a standard rear section married to a lowered chassis frame ahead
of the rear axle, and third, the relocation of the engine to the offside
of the bus.
- These alternative layouts lead, respectively, to the presence
of a sloping floor at the rear of the bus, two or three steps to link
the front and rear sections, or the achievement of a near 100% low gangway
from which some seats are reached by a step. Future developments, such
as the use of hub-mounted electric motors, will lead to the production
of completely low-floor buses.
- The Committee has previously expressed concern about floor
slopes, but trials of various low-floor bus types in the UK and the
experience of other countries demonstrate that a reasonable floor slope,
away from the low-floor area of the bus, can provide an acceptable alternative
to steps in the gangway. However, any such slope needs to be confined
to the rear of the vehicle.
- Experience has shown that a kerb height of not less that 150mm
is desirable to achieve the full potential of low-floor buses. Even
where pavement heights have been raised to minimise the vertical gap
between the kerb and the bus, it will not always be possible for the
bus to reach the kerb at stops. For wheelchair users, some form of boarding
aid is therefore essential. A power-operated ramp probably represents
the best solution, and various types are now available to suit one or
two-door vehicle designs. A manually operated "fold-out" ramp requires
the driver to leave his cab. The choice between powered and manual ramps
will largely be dictated by the nature of the route or services operated
(e.g.: urban/rural; frequent or limited stop) and the running time available.
Alternatively, in areas without kerbs, a power-operated lift may be
appropriate.
- All the following recommendations take account of experience
with low floor buses in the UK and draw heavily on the work of the European
Commission COST Action 322. DPTAC may revise this specification as further
designs of low-floor bus become available.
- Where low-floor buses are to be introduced the Committee urges
consultation with potential users (including local groups representing
those with impaired mobility) and with local authorities to ensure that
the needs of all passengers are taken into account.
- The inherent advantages of the low-floor bus can only be fully
realised if its use is co-ordinated with a concerted drive to eliminate
illegal parking and improvements in facilities at bus stops. In conjunction
with full publicity and thorough driver training, including disability
awareness, and motivation of all the staff concerned, the Committee
believes that the image and success of local public transport can be
greatly enhanced. A consistent partnership approach between operators
and local authorities is required.
The Specification
- Unless modified by the paragraphs below low-floor vehicles
must meet all the requirements of the DPTAC
Re-statement of Recommended Specification for Buses Used to Operate
Local Services (revised July 1995).
- Low-Floor Area:
2.1. In single-deck vehicles at least 50 % of the floor space
available for passengers (i.e. excluding driver's cab and wheelarch
boxes) must form a single area, without steps, with access to at least
one door (or two where entrance and exit are separate). In the case
of double-deck vehicles this requirement applies to at least 35 %
of the lower deck floor area available for passengers.
2.2. With the vehicle in its normal ride position, this area
should ideally be flat but may have a maximum slope of 5% (about 3°
or 1 in 20) in any one direction over short distances. Within one
metre of any door, however, a maximum transverse slope of 8% ( about
5° or 1 in 12) is acceptable. Compound floor slopes must be avoided.
2.3. All seats in the area described above (with the exception
of those mounted on wheelarches) must be fitted in such a way that
there is no footstool.
2.4. A minimum clear width of 800mm at floor level must be
provided from the entrance through the wheelarch area, and therefore
of 750mm at floor level and at least 800mm from a height of 450mm
above the floor, so that a user of a wheelchair to ISO Standard 7193
(1200mm long by 700mm wide) is able to manoeuvre between the bus entrance
and the designated space (See 3.1).
- Wheelchair Space:
3.1. A space must be provided into which
a wheelchair-user may manoeuvre and travel safely, facing the rear
of the bus, parallel to its bodyside, and backed up to a transverse
padded backrest. This space must be level and free of obstructions
and at least 1300mm long and 750mm wide at floor level, to
accommodate wheelchairs to ISO Standard 7193. [See Figure 1 below].
Any additional space(s) for wheelchairs or pushchairs should be located
to the rear of the first space (on either side of the bus) so that
the first fixed transverse seats are as near as possible to the bus
entrance.
3.2. The padded backrest should be 300mm wide and may be inclined
up to 10° from the vertical into the wheelchair space. It should extend
vertically from 480mm above the floor to a height of 1300mm above
the floor and be fixed in such a way that the rear wheels of a wheelchair
may fit either side, with the back of the chair close to or in contact
with it. This can best be achieved by centring the backrest between
the sidewall of the vehicle (allowing for the space taken by any tip-up
seats - see 3.6) and a vertical floor to ceiling handrail fixed 750mm
out from the sidewall and 550mm from the end of the wheelchair space.
Where necessary, to improve wheelchair access this handrail may be
fixed 400mm from the end of the wheelchair space, but only to a maximum
height of 600mm from floor level. The 550mm dimension must apply above
a height of 775mm from floor level. [See Figure 1 and Figure 2 below].
3.3. A horizontal handrail should be fitted at the sidewall
850mm to 1000mm above the floor, from a point 550mm back from the
leading edge of the padded backrest for the remainder of the wheelchair
space. A further horizontal handrail should be fitted 1200mm to 1500mm
above the floor to be within reach of any passengers standing in this
area.
3.4. The provision of the padded backrest and the vertical
and horizontal handrails referred to above is designed to ensure that
no clamping or restraint mechanism is required. However, users must
be clearly instructed by suitably-worded signs incorporating a pictogram
that it is their responsibility to apply the wheelchair brakes or
isolate its power supply.
3.5. A separate push button to request the operation of the
wheelchair access ramp (see 4.2) should be fitted within reach of
the wheelchair user, at a height of 850mm to 1000mm above the floor.
This button and its surround should be in different colours to those
used for bell pushes throughout the bus and the button should be marked
with the international wheelchair symbol. A notice adjacent to the
button should explain its use, and the driver must receive a clear
indication that it has been operated.
3.6. Tip-up seats may be fitted in the wheelchair
space longitudinally along the sidewall or transversely at the opposite
end from the padded backrest. A single tip-up seat may be incorporated
into the lower part of the padded backrest, in which case the dimensions
of the backrest may be amended to a width of 425mm up to 830mm above
the floor. A minimum of 360mm clearance is required below the tip
up seat (See Figure 2 below). Tip up seats must be between 430mm and
460mm above the floor when in use. Suitable signing is required to
request passengers to vacate the tip-up seats if a wheelchair user
or someone with a pushchair needs the space. Tip-up seats must not
be designated as priority seats for elderly or ambulant disabled people.
(See 8.1).
3.7. Suitable interior mirrors (or other equipment eg. CCTV)
should be provided to enable the bus driver to observe the designated
wheelchair space from the driving position.
- Boarding Aids:
4.1. "Kneeling" suspension is essential on all low-floor buses
and must always be used to ensure that the step height at any door
does not exceed 250mm. Care needs to be taken to ensure that the selected
kneeling configuration does not worsen the gradients in the door area
on the access ramp, or at the interface between the two.
4.2. The access ramp must be capable of
taking a minimum weight of 300kg and should ideally be designed to
ensure that when the bus is 'kneeling' there is a maximum gradient
of 8% (about 5° or 1 in 12) from the kerb. A gradient of up to 12%
(about 7° or 1 in 8) may be encountered where the kerb height is less
than 125mm. In some operating circumstances it may not be possible
to avoid steeper gradients and where these occur a wheelchair user
may require assistance. The transition from the ramp into the bus
must avoid severe changes of gradient, and every effort must be made
to eliminate any vertical projections at the point where the ramp
links to the floor in the doorway. The ramp must be capable of extending
to ground level.
4.3. The ramp must be not be less than 800mm wide and not
more than 1050mm long, and have a surface which provides good grip
in all weather conditions. Warning notices should be displayed to
prevent passengers boarding a moving ramp. An audible warning device
must be used to alert pedestrians whenever the ramp is moving.
4.4. If a power-operated lift is used as an alternative to
a ramp it must be capable of taking a minimum weight of 300kg, and
be at least 750mm wide and 1200mm long when deployed.
- Doorways:
5.1. The specified dividing handrail cannot be provided at
any doorway used by wheelchairs or unfolded pushchairs. Such doorways
must have a clear width of at least 800mm and if not within the driver's
direct field of view, a push button must be provided on the outside
of the vehicle adjacent to the door to request operation of the ramp.
This button must be mounted between 1100mm and 1250mm above road level,
be capable of operation with the palm of the hand, colour-contrasted
with its surroundings and illuminated when ready for use.
- Interior Steps or Slopes:
6.1. From the rear of the second doorway (or where one would
otherwise be fitted in the case of a single-door vehicle) a sloping
gangway towards the back of the bus may be used, as an alternative
to internal steps. Its gradient must, however, be a maximum of 8%
(about 5°or 1 in 12) and the floor covering throughout the area of
slope must be colour contrasted with the rest of the vehicle floor.
To avoid the need for more than two steps (maximum 200mm each and
grouped together) between the low-floor area and the rear part of
the bus, a sloping gangway may also be provided from the top step
but with a maximum gradient of 5% (about 3° or 1 in 20). The seats
on both sides of any sloping gangway and adjacent to any step must
all be fitted with a vertical handrail from seat back to ceiling.
- Handrails:
7.1. The positioning of handrails throughout the vehicle requires
careful attention. In the absence of steps at doorways, handrails
fixed to the inside of the door leaves or to the bodywork in the door
area should consist of a vertical component from 500mm above the floor
to a height of 800mm to 900mm, turning into a horizontal section which
extends at least as far as the width of the door leaf. Similarly,
where a centre dividing handrail is provided in any doorway of sufficient
width and not required for wheelchair access, it should rise vertically
from the floor for 800mm to 900mm (from a point 100mm inside the step
edge) and then turn to the horizontal, extending for up to 600mm before
returning vertically to the floor. [See Figure 3 below].
7.2. The specified maximum distance between handrails of 1050
mm may not be achievable in the area required for a wheelchair to
be manoeuvred. In any part of the bus where the spacing of vertical
handrails is greater than 1050mm, high-level horizontal handrails
at a minimum height of 1900mm above the floor must be provided and
fitted with suitable loops or hanging straps. Alternative arrangements
such as "looped" handrails from ceiling to bodyside may be considered.
- Seating:
8.1. The specified provision of priority
seats may need to be adjusted to ensure adequate manoeuvring space
for wheelchairs. As a minimum, three fixed seats (forward or rearward
facing) which meet the requirements of the Specification must be clearly
designated for use by elderly and ambulant disabled passengers.
- Exterior Signing:
9.1. The standard international wheelchair symbol (white on
blue) should be displayed on the front of the bus so that wheelchair
users are able to recognise accessible vehicles.
Updated: 9 November 2000
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